Isoflurane-induced protection against myocardial stunning is independent of adenosine 1 (A(1)) receptor in isolated rat heart

Volatile anaesthetics can pharmacologically enhance the recovery of stunned myocardium, but the mechanism is still unknown. This study sought to deter mine whether isoflurane attenuates myocardial stunning, and whether the myo cardial protection of isoflurane is mediated by adenosine A(1) receptors. F ive groups (n=8) of isolated rat hearts were studied in the Langendorff app aratus. The control groups underwent 20-min ischaemia with or without adeno sine receptor antagonist (DPCPX, A(1)selective) treatment (Cont group and D PCPX group). In the isoflurane groups, isoflurane (1.5 MAC) was present thr oughout the experiment (Iso group) and DPCPX (200 nM) was administered from 10 min before ischaemia (Iso+DPCPX(pre-1) group) or the beginning of reper fusion (Iso+DPCPX(post-1) group) to the end of experiment. The isoflurane g roups had a lower end-diastolic pressure than the control groups (P<0.05). Developed pressure recovered to 77, 76, and 82% in lso, Iso+DPCPX(pre-1) an d Iso+DPCPX(post-1) groups, respectively (P<0.05 compared with control grou ps). LV+dp/dt(max) recovered to 53, 86, 81, 84, and 60% of pre-ischaemic va lues in Cont, Iso, Iso+DPCPX(pre-1), Iso+DPCPX(post-1), and DPCPX groups. L V-dp/dit(min) recovered to 55, 84, 83, 81, and 62%, respectively. Both LV+d p/dt(max) and LV-dp/dt(min) were significantly different (P<0.05) between c ontrol and isoflurane groups during reperfusion. There were no significant differences among the isoflurane groups. Our data show that isoflurane enha nces the postischaemic functional recovery of isolated rat heart and that b lock of A(1) receptors does not abolish the beneficial effects of isofluran e. We conclude that A(1) receptors are not involved in isoflurane-induced m yocardial protection in the isolated rat heart.